Baskets are used to retrieve biological material from the body. Baskets are used, for example, to retrieve stones from the urinary tract (e.g., ureteral stones) or stones from the biliary tree (e.g., bile duct stones). Baskets may or may not be used through a catheter, an endoscope, or a laparoscope.
Existing retrieval baskets generally consist of legs, and the diameter and overall shape of the basket is defined by the number, flexibility, shape, and length of the legs. The legs generally are equal and fixed in length, providing overall symmetry to the basket shape. The legs of the basket typically are joined at the tip of the basket and at the base of the basket closest to the sheath. The legs can be joined with solder, by welding the legs together, or by some type of mechanical mechanism. At the basket base, the joined legs typically also are attached to a shaft, wire, or coil. The shaft can be moved back and forth within the sheath or catheter by an actuation device such as a proximal handle with a back-and-forth hand-activated slider. Alternatively, the sheath can be moveable back and forth to expose and cover the basket. In any case, the basket is exposed and expanded fully, within the sheath and collapsed fully, or somewhere in between those two extreme positions, and the legs generally all move in a collective manner as they are joined at both the tip and base to form the basket.